I am new to HL7 and the first thing that came to my mind was, why isn't this format using XML instead? There are a handful of parsers and there are some serious inconsistencies among vendors.
For those new to the health care software business I recommend this read http://www.interfaceware.com/hl7_version2x.html
HL7 version 3 is using XML. Earlier versions of HL7 are a health care specific derivative of a pipe delimited format (IIRC its called ER7, not sure though).
Theres nothing particularly wrong with the pipe delimited format. In many ways the newer XML variations are harder to use. It may be old, but for the most part it works and it is well understood.